Conventional speed control devices include a fixing member for securing the device to the bicycle frame and rotatably to the fixing member the lever body for actuating the derailleur. The lever body is rotatably supported to the fixing member. As is well known the device includes a positioning mechanism comprising a positioning member having a plurality of engaging portions, an engaging member engageable with one of the engaging portions, and a spring for biasing the engaging member toward the engaging portions, and a friction mechanism for applying to the lever body a rotational resistance against a return spring of the derailleur.
The conventional speed control device has independently either the positioning mechanism or the friction mechanism, but a device building in both the mechanisms has not been proposed. However, the present inventor has previously proposed a device provided with a positioning mechanism and a change-over mechanism having an operating member for changing over a positioning member of the positioning mechanism from the operating position thereof to the non-operating position, so that when the operating member is operated to change over the positioning member to the non-operating position, the lever body is given a rotational resistance against the return spring of the derailleur.
Accordingly, the above device can desirably select a case where the positioning mechanism is used to set the respective speed change stages for changing the speed and that where the positioning mechanism is not used but rotational resistance is given to the lever body, thereby changing the bicycle speed at a desired operating position of the lever body. For example, even when a control wire expands, its length is not adjusted, but the device is changed over to the speed control by the rotational resistance or friction, thereby enabling accurate speed control.
The above device can change over the positioning mechanism to the operation position and the non-operating position, but the positioning mechanism and change-over mechanism are incorporated together with the lever body in the fixing member by forwardly screwing a clamping bolt, whereby the operating member is limited to its operation range. Hence, the resistance against engagement of the engaging member with the engaging portion of the positioning member and the rotational resistance given to the lever body when the positioning mechanism is changed over to its non-operating position, are nearly decided, so that a high processing accuracy is required for each component and it is difficult to adjust the engaging resistance and rotational resistance as desired.